1. Field of the Invention
This invention relates to Private Branch Exchange (PBX) switching systems and, in particular, to circuitry for providing call override or butt-in capability.
2. Description of the Prior Art
In prior art PBX systems the ability of a calling party to override a conversation between a called party and a third party required the calling party, upon receipt of a busy tone, to hang up and then dial a special override code followed by the directory number of the busy called party. One of the disadvantages in implementing call override in this manner is that the calling party must first hang up upon receipt of the busy tone. Another disadvantage is that special circuitry must be provided in the PBX to recognize the special code required to initiate a call override sequence. A third disadvantage is that the calling party must redial the directory number of the busy called party once the PBX system has been alerted that a call override request has been made. These disadvantages make the provision of call override expensive in both the amount of time required to effect an override and in the amount of equipment needed to supply this feature.
Accordingly, it is one object of the present invention to reduce the amount of time expended by a calling party in effecting a call override to a busy called party.
Another object is to eliminate the need for the calling party to redial the directory number of the busy called party.
A further object of the present invention is to reduce the amount of PBX system equipment required to provide a call override feature.
Yet another object is to eliminate the need for the calling party to first hang up and then dial a special call override code.